The treatment and management of bone defects remains one of the most challenging aspects of orthopaedics. Bone defects occur in a wide variety of clinical situations. Restoring natural anatomical length and shape of any long bone with a bone defect is problematic. Additionally, whenever a vertebra has to be removed, it is necessary to insert a vertebral spacer to restore the natural length and curvature of the spine as well as to promote bone fusion. Restoring spinal anatomy and stability and promoting bone fusion are even more difficult in a corpectomy, a surgical procedure in which a section of one or several vertebrae is removed.
Many different implants have been developed for use with bone defects. So-called “mesh implants” have shown to be particularly effective. One such implant is the SynMesh™ available from Synthes (USA) of Paoli, Penna. The SynMesh™ is a titanium mesh cylinder which is provided with a plurality of uniformly-spaced apertures of uniform size distributed on its surface. In order to address the different clinical situations in which bone defects arise, the SynMesh™ is available in a variety of lengths and diameters. Commercially available allografts for treating bone defects have recently become available.
Although the clinical results of mesh and allograft implants have generally been positive, one possible clinical complication is subsidence of the implant. Excessive sinking of the ends of the implant into the bone with which they contact is especially troublesome whenever the bone is extremely porous. From both a mechanical and physiological point-of-view, it would also be advantageous to increase the surface contact area between the implant and bone. U.S. Pat. No. 5,702,451 to Biedermann et al. discloses end rings that attempt to address these concerns. However, the end rings disclosed have no provisions for holding, insertion, and distraction instruments. Thus, implantation can be difficult. Furthermore, there can be excessive movement between the bone and the disclosed end rings after implantation. This may delay, and perhaps prevent bone fusion.
As the discussion above illustrates, there is a need for an improved end member for use with a bone fusion implant.